When a bully picks on you, you might get consoled by grown-ups who say things about how he's just jealous or trying to get your attention. But now a group of psychiatry researchers at the University of Chicago have revealed the true reason behind bullying: That bully beats you up because he enjoys it. Healthy kids' brains (pictured) respond to other people's pain with sympathetic twinges in their own pain centers. But bullies who witness pain show activity in their brains' reward centers. Psychology professor Jean Decety and his team analyzed the brains of bullies — teens who had showed unusual aggression, starting fights, using weapons, and mugging people. He put the bullies in a functional MRI scanner, looking to see how their brains reacted to pictures of a person deliberately stepping on someone else's foot. Said Decety:

Aggressive adolescents showed a specific and very strong activation of the amygdala and ventral striatum (an area that responds to feeling rewarded) when watching pain inflicted on others, which suggested that they enjoyed watching pain.

Earlier this year, Decety demonstrated that most children respond to these images of pain with sympathy, imaginatively feeling the pain themselves. And that's what the control group in his most recent study did. But the bullies clearly liked seeing pain. Decety thinks his discovery will help psychologists and psychiatrists treat violent adolescents. He believes that when teens enjoy other people's pain it means they've suffered a disruption in their brains' natural empathetic reactions. In other words, someday we might have a "cure" for aggression that restores bullies' ability to feel sympathy for other people's pain. Of course, tinkering with this brain signaling mechanism might also reveal a way to disrupt people's empathy too — turning pacifists into sadists. Source: "Atypical Empathetic Responses in Adolescents with Aggressive Conduct Disorder: A functional MRI Investigation" [via Biological Psychology]